Power transmission



Feb. 13, 1940. 0.1:. MOHLER 1 9 POWER TRANSMISSION Filed Feb. 18, 1937 s Sheets-Sheet 1 Fe 13, 1940. D QMOHLE'R 0, 2-

PowEnmRANsmssIon v Filed Feb. l8, 1937 e Sheets-Sheet 2 Feb. 13, 1940. D. D. MOHLER POWER TRANSMISSION Filed Feb. 18, 19:7

6 Sheets-Sheet 5 Patented Feb. 13, 1940 Qt l mqg iom hem so in broken..-alva;' and s DQSQ t1 oemtheideta new! U Q 0 the aut m ti Like reference characters designate corresponding parts in the several figures of the drawings. Referring first to Figure 1, the transmission essentially comprises a pump unit generally designated l, and a motor unit generally designated 2, each of these units being preferably of a type applicable to the utilization of a hydraulic medium or working fluid which serves to more or less flexibly interconnect the same so as to trans- 19 mit power from a driving member generally designated 3, to a driven member generally designated 4. Suitable controls are provided for regulating the transmission ratio, and these controls may be either of the manually operated type or u or the automatically operated type. as will hereinafter become more fully apparent. For convenience, the description of the manual and automatic types of transmission will be treated separately. U Pump unit The pump unit i will now be described, and it is to be understood that the same wnstruction may be employed for either the manually controlled or automatically controlled type of transmission. The pump unit is preferably housed in a stationary outer shell or casing i and an inner rotary shell or casing I, the latter casing containing the principal working parts of the pump. As will be clearly apparent from the drawings. the pump itseli is essentially of a planetary gear type, including a'hollow central or maingear I, with w ch there is meshed one or more planetary he cal gears 8. These planetary gears a may be either single or double, and at least two such gears are preferably provided for the sake of balance. If twosuch planetary gears are employed, they will of course be arranged at diametricallyopposite points respecting the main or central gear I. As shown, the planetary gears on I are each rotatably mounted on a shaft which in turn is seated at its opposite ends in bosses ll formed in the shell I and cavities ll formed in a head It. The head I! is fixedly secured in any suitable manner to one end of u the shell 8 and closes the corresponding end of the shell. Formed on the head I! and projecting inwardly of the shell 6 is a stud or stub axle it, which is received within a bearing ll set in the adjacent end of the central gear 1. l0 On the opposite side of the head If is formed a hub I l, which lsreoeived in a thrust hearing it set in a head l1, the head il being suitably mounted on and fixed to the outer shell I so as to close the corresponding end of this shell. 86 The hub I! is bored to receive the driving member 3, whibh extends through a suitable opening'provided therefor in the head I1. The driving member may be keyed, splined, or otherwise suitably flxed to the huh I ii at one end. and the outer end of the driving member s is adapted to be connected to any suitable source of power or'prlme mover, such as, for example, an internal combustion engine generally designated E, shown in Figure 10, by way of example. .Of course, the transmission is not limited to use with internal combustion engines as will becomemore obvious as the description proceeds.

As previously'mentioned, the main gear I of 70 the planetary gear, pump unit is hollow for a major portion of its length. One end, however,

is closed, as at it, and the other end is extended in the form of ,a tube lQ, which is likewise hollow, and continues into the motor unit 1 '5 2, where it is positively connected to said .motor gated diaphragm it, this diaphragm It in turn carrying a so called labyrinth ring 24, having sealing engagement with the adjacent end of II the pump casing t, as at ft. The ring :4 is

secured to the diaphragm it by means of the stud bolts 2 or equivalent fastening devices, and it will be observed that the ring H, as well as the corresponding end of the pump casing I. are each open to provide an annular fluid passage 21 about the tube it. This passage 21 communicates at oneend with the interior of the pump casing I, and at its other end with a chamber 28 adapted to contain a working fluid "or hydraulic medium, such as oil. Passages I direct the working fluid to the far ends of the gears I, while the near ends of the Hears are substantially in direct communication with the passage 21. Thi working iiuid may or may not be a wholly sell -contained in the transmission, as desired. It would be within the spirit or the invention to provide an auxiliary reservoir for the working fluid, having communication with the chamber a. but ordinarily such auxiliary reservoir is not necessary inasmuch as there is no. appreciable loss of the working fluid once the transmission has been tilled or charged with the iluid. The same working fluid is circulated and recirculated through the transmission by 0 means of the pump unit.

In operation, rotation of the driving member t causes the head I! and the shell 8 carrying the planetary helical gears 6 to rotate. it the central gear I is stationary, or if there is any I appreciable relative I motion between the planetary gears and the main gear, the working fluid which is admitted into the interior of the casing 6 from the chamber fl through the passage 21, and which this the interior of the casing I, will 60 be forced through the ports into the hollow .main gear I, and thence through the tube It to the motor unit 2, which will now be described. The pumping action of the pump unit should be obvious from the foregoing, and further descrlp- 56 tlon of the pumping action or principle of operation of the pump unit is believed to be unnecessary.

Motor unit (manually controlled type) The principal parts of the motor unit are the central or main gear 29 and one or more auxiliary gears 30, these gears being all preferably of the double helical, continuous tooth type, and constantly remaining in mesh with each other, as the same as the gears of the pump unit. In the motor unit. however, the auxiliary gears 30 as shown in .the exemplary form of the invention disclosed herein are mounted on fixed axes so that they have no planetary motion with respect to the central gear 2!. This central gear 29 is positively and rigidly connected with the central gear 1 of the pump unit. this positive connection belngestablished by the tube II, the motor end of which tube is threadedly or otherwise suitalarm s ably connected the main gear 2!. 'Ilhe main gear "is hollow. and within the same, adjacent of the working fluid along the shaft4 tothe outto the end of the tube i4. is provided a spider or a series of web-like spokes 'li which serve to support a central hub". The hub I2 isin turn rigidly connected to the output shaft]. sothat. the shaft 4 will be rotated. pursuant to rotation a. of the main gean lih The main gear. pas previously mentioned.

is preferably hollow and preferably, ground to have a close runninglnt over a sleeve II, forming apart ofthe head 34,.thehead 84 beingtadapted to be rigidly secured to the motorqcasing I. and closingthe power output end of themotor casing. It will be observed that the sleeve 1flisoi substantial length. and the close fit .betweenthe same and 1 the main'gear 2| forms an effective seal and prevents. the escape of the hydraulic medium or working'iiuld fromthe'highpressure side to the low pressure side of thewgearspas will hereinafter become more apparent-J Also formed'on. the head 84 is anothersleeve 86. through which the output shaft 4 extends. and this sleeve 8! acts both as a bearing for the shaft 4 as well as a seal to prevent-the escape side of the transmission. In other words. the

sleeve 35. like sleeve I3. is of substantialylength and has a closelworking fit withthe shaft 4.

This fluid seal afforded by the sleeve ll is fur- .ther augmented by the provision of packing rings 36 which are backed up by a gland i1: and wmain tained in effective sealing adjustment by, the

The auxiliary gears I0. of .which there are preferably two. for thesake of balance. are preferably hollow to 1 reduce their weight. 'andeach;

is provided at one end with an axle or stub shaft 38. which is Journaled in a bearing-set in the inner face of the head 34. 1 In the'oppositeend of each of the gears 30. there is provided ab'earing 4i, in which is received a fixed spindle or bearing lug 42. forming a part of a spider. 48

. disposed intermediate theworking parts of the pumpand motor units respectively. This spider Hisprei'erably fixedly mounted in the end of thehousing or outer shell of the motor unit. and preferably carries oneor more bearings to take the endwise thrustswhlch may be imposed upon the central or main gearsof the; motor and pump units. As shown in the drawings. two

thrust bearings 44 and .4! maybe employed.

and these thrust bearings further aid in keeping the main gears of the pump and motor units and the interconnecting tube is properly aligned. It will be obvious that the bearing arrangement maybe modified if desired, and it is to be understood that I do not wish to be limited. to the precise arrangement illustrated and specifically described herein. i i I i The motor unit casing 2 is further. provided with suitable fluid passages and cylindrical bores,

the latter constituting valvc chambers. which will now be specifically described. For each of the auxiliary gears 30 of the motor unit. thereis a corresponding valve, chamber ,46. and leading I -i'rom each of thevalve chambers 48 to the-Juncture of the central gear 29 and each auxiliary gear SiLis-a series of ports or passages 4! arranged in a row, which passages serve to admit the hydraulic medium or working fluid which is directed from the motor end of the tube l0.

. through the annular passage 4!. and thence into the valvechambers 48, to the motor gears 20,40,

30. In each valvc chamber 46, there is mounted a rotary. valve 4.. These valves flare each mounted upon'ashaft ".one end of. the. shaft being iournaled. in the .motor housing. .asat Ii,

naled in and extending through the head 34...

and theopposite end ofthe shaft being iourat If. Preferably, a labyrinthseal isyprovided.

seat 53, to prevent the escape of theworking fluid through. theshaft bearing. in the head 84. ,The body of each valve is. partly cylindrical in transverse cross section. and inaddition. the 1; body is cut away to form oppositely inclined sections l4 and". sothat uponlrotationliof the valve body; the ports or-passages 41 will be successively closed or openedpaccording to the direction Mutation of the valve. It will be obvious, of course. that each of the; tapered sections, 84

manner as the shaftwllof each valve ;4l.- In other words. one end of the shaft II is journaied in the motor housing.l as at 40. and the opposite -end of the shaftis iournalediin and extended through the head I4. as at 4i. Preferablym. labyrinth seal" is provided for each shaft)". the same as. in thccase of the shafts 80, as best seen in Figure 8. Leadingfrom each valve chamber 51. is a series of lcngitudinalslotsll. :ar-

.ranged in a row. and constituting ports adapted to establish communicationv between the respective valve chambers ll andlongitudinal fluid passages 14. These (fluid passages 64. lead through the motor housing from the head end to the opposite end. where they are -openand communicate with the iiuidchamber 28,.=previously referred to in the description of the pump unit. it being understood that the spider 48 is provided with openings vtherethrough to allow the working fluid to freely-pass from the passages 44 to the chamber 24. m 1 up The valve'body of each of the vaivesyll is a partial cylindrical shelhso that byrotating the shafts ".therespectivc valve bodies wilLclosc or open the ports ll asdesired. These valves; 88

may be generally termed "by -pass" valvcs.-inasmuch as they serve. to. either allow the working fluid .to .be circulated from. the i chamber 28 through. the pump unit I to the motor unit 2. and back againio the chamber 28. without acting upon the motor gears. or with agesulting driving action imparted to the motor gears, according to the adjustment of the valves 68, either respectively opening theports 83 or closingthesc ports.

l au

According to the construction illustrated in Figure 8. which best shows the manuallycom trolled typeoi transmission .motor' unit. the two valve shafts. and the twoby-passvalve shafts iii. each have mounted on their free extremities sprockets II and, respectively. arranged in the l same. transverse plane. an additional sprocket 61 mounted on a shaft ilg supportcd by the head 34 is also provided, and about these ilvcsprhckcts is trained a chain i not shownihwhich serves. to

interconnect the valve shafts so that rotary motion. of shaft is transmitted to the various valve shafts. In other words, shaft ",may be connected at its free ,end to any suitable manuyally operablemechanism (not shown) ,by means of which the shaft 68 may be adjustably rtat'ed, and this adjustment of shaft 68 is in turn transmitted to the various rotary valves previously described. i9 designates a cover plate which serves to enclose the sprockets- 65', 66 and 61,

and their ChainQThe cover plate is provided with a suitable opening through which shaft 68 extends far enough to permit its connection to any desired type of mechanism by which rotary cover the ports 63. In such "a casefthe working fluid will merely circulate through the transmission without acting upon the gears of the motor 'unit, as will be readily understood from the foregoing description of the function of the by-pass valves i ly that'is to say, the working fluidwill be by-pass'ed around themotor gears and caused to be continuously circulated in'a closed path between the pump and motor units, the circulation resulting from the action of l the planetary gear pump upon the'working fiuid. To tran'smitpower to. the output shaft 'l, the manual controls must be adjusted to such a position that the bypass valves 58' close the ports 63; When these ports are closed, the working'fluid must then enter the valve chambers 48, from which chambers the working fluid is directed through the ports 41 to the motor gears 28, 10, 30, under the control of the valves 49; The pressure of theworking fluid created by the-pumping action of the gear pump will set the 'gears of the motor'into operation, thus delivering power to theoutput shaft ,vby reason oi the fact that this shaft is rigidly connected to the'central gear 29'of'the' fluid, this gear is rigidly connected by the tube is tothe central gear 1 of the pump unit, and causes this: central gear! to rotate along with it. The relative motion of the planetary gears '8 of the pump unit respectingthe central gear] will be at its maximum for power transmissionpurposes, and causes the working fluid which'is circulated through the transmission by the pump unit to flow at the maximum rate, which just meets the requirements at the output end of the motor unit, which is to say thatthe slip of the working fluid is maximum when the conditions are as just described. The transmission is now working at the lowest'ratio, which ispositive and fixed by the particular design. In. other words,"

the range 10f transmission ratio is determined by the size and number of the passages, the size'and shapes of the ports and valves, etc. I

To increase the transmission ratio from the lowest limit just described, it is necessary to furtransmission' ratio will beaincreased.

'ing ratio changes.

the! adjust the position of the valves v4! so as to close one or more of the-ports 51 according to the degree of change desired in the transmission ratio. It will be understood, however, that al-- though the valves 49 may now have their positions changed, and these valves are interconnected with;the by-pass valves 58, the change in the position of the by-passvalves does not open the by-pass ports 63; that is to say, so long asthetransmission-isoperated to transmit power'from the input side to the'output side, the bypass'valves ,58' must remain closed, irrespective of adjustments of thevalve's 49 to vary the transthe interconnected sprockets and chain.

Having assumed that the valves 49 have been "further adjusted to close some of the. ports 41, it

will be understood that all of the fluid being pumped must be fed'to the chambers which arev in commrmication with the open ports, resulting ina building up of pressure-and causing gear 29 to rotate at a faster speed, thereby cutting down the discharge of the pump until a state of equilibrium is reached where the pump discharge equals the motor capacity. In other words, the

rate 'of"circulati'on of the working fluid under the influence of the pump unit will be reduced to justathat amount required to meet.the'demand at the output end of the transmission, and the Further adjustment of the valves 49 to close'additional ports 41 will'further vary the slip of the working fluid, and consequently further increase the transmission ratio. Obviously, the change in the transmission ratio will be uniform and smooth, and power will be continuously transmitted dur- By reason of the fact that the circulation of the working fluid is stabilized when'each adjustment-bf the valves 49 is made,

there will be a positive transmission ratio established for each adjustment, which will depend' upon the particular designof the transmission which, of course, can be varied to meet any predeterminedtrequirements. It may be seen that the torque will vary substantially in inverse pro-' portion to the speed of rotation, and therefore the power output remains substantiallyconstant over the entire range of adjustment of the transmission ratio which is much tobe desired in many fields of application of power transmissions.

By still further adjusting the valves 49 to a position closing all of the ports ",the maximum transmission ratio is attained; that is to say, a 1&1 ratio is established. In such a case, the working fluid has no circulation, and merely remains in a static conditionin the various parts of the transmission. The gears of the pump unit become virtually locked together through the trapping of the working fluid in the gear chambers, and there being no relative motion, under.

such a condition, between the central gear I and the planetary gears 8 of the pump unit, no pumping action is created, and the gears merely rotate together as a unit, thereby transmitting the power hump unit (automatically type) r are essentiallyjthe same for both the automatic andmanual types of transmissions, as previeusly mentioned, the pump unit-is preferably slightly modifledjin its adaptation to an automatically controlled transmission. The modifications re-v side in the provision of a small earp n ene orally. designated A, and best; seen ,in Figures *1 and 2, which is mounted within thc outer casing [of the pump unit,.and 'alsolsuitable passages leading toand from this small'purnpunit. The

3 gear pumpA is'comp o'sed of three small gears 10, II and I2, arranged in intermeshing relation, 1 and one of which, preferably the middle gear II.

is provided with an extended shaft 13, on which ".is mounted a sprocket I4 adapted to be driven by the input shaft 3 of the main pump unit through the intermediary of a sprocket ,Ilflxedly mounted on the hub I5 and interconnectedwith sprocket u by means or a chain". I The small ears in.

I prov; ed on the interiqr II and I2 areset in recesses boredin a boss 11 I V i the housing 5, and a cover plate I8 having suite-ole provision for being and :id thesarnein place, it being understood that the gears are provided with hubs or axles extending from opposite sides thereof and respectively, journaled in the boss 11 and, the cover I8. This pumpA communicates at its intake side with I the working fluid chamber 20 through passages use, an and :2. so that working fluid is drawn from the chamber" when the gear pumpA is I in operation, and is discharged from the pump A through passages and 84. Obviously, the rate at which the working fluid is discharged from the j small pump A will depend upon the speed of the I the drive shaft 3. m

pump, which, in turn, depends upon the speed of Motor unit (automatically controlled te As in the ase or the pumpunihthe principal working parts of; the motor unit for an automatically controlled transmission are the same as those previously described for the manually controlled type of transmission. In certain respects,

however, the following modifications, are prefer- 'ably made Mounted in thelieadfl of the motor unit 2, as best seen in Flguresl, Sand '7, is a small gear pump B which'is similar to the small gear pump A of the main pump unit I. This gear pump B comprises three gears 85, 80 and 81, having their axles respectively journaled in eTboss 88 formed on the head 34, and in a'cover plate 89.

One of the gears of the pump B, preferably the central gear 86, is driven directly from the shaft 30 of the auxiliary gear 30 or the motor unit, and

.t the pump B receives working fluid from the motor by pass are substituted by a port 96 which controlled by the by-pass ,valve' 95, as will bebest ,casing 2 at the intake side of thepump through passages 90, II and 02. i The smallpump B discharges through passages 93 and 94 formed in the cover plate ",as best seen in Figure In lieu of the manuallyoperable JV-P855 valves I ll in the valve chambers II, an automatically ,controlled by-pass valve 90 issubstituted in the automatically controlled type of motor unit. Also, the ports 03 of themanually controlled type of chamber lli of'the cylinder 91. Another fluld fluid line of the automatic control system; and at the otherlend with an endof the cylinderil'l,

as seen in Figure 13,.is;provided in themotor,

housing 2. i The by.passvalve :95 has fixed thereto a stem I02! which extendssinto the chamber I00 of, the cylinder 91, and on the end of this stein I02, oppositeto the lay-pass valve 95; lea-piston be withdrawn from Fori the purpose of for the manually controlled typeiof motorlunlt,

thereare provided suitablefluid operated rneans connected to" the yalve' shafts 50,1through,the ln- I termediary of; arackand pinion These partsof the automatic control system are .bestseenwln Figure 7, wherein I designates a cylinder, formed on the motor head 3landhaving a piston cham- 5 passage IOI communicating at one endwlth, a While the principal parts of the pump unit I I i ber I06 therein. One of the fluid lines jo f the automatic control,system isadapte d to bijconp;

at its end opposite to thepiston I09. This rack I I I meshes with a pinion I I2fixedly mountedpn the outer end of the valve shaft 50. Aswillbe readily understood, thecylinder I05,'pistoril09 nected-at lfll'too ne end of the cylinder 105;; and fluid is allowed to enter the chamber. I06-t ough and rack and pinion means 'II I and II IQare I I3 designates a removable plug,

H2 which is recessed within aprotuberant houswithinthe piston chamberl fli normally urges the piston I09 and racl;meanstowardsthe limit of its movement in one direction, that is, the dilf ectioncausing rotation of the valveffl9 to a position is which I call a pilot'valvePV. The construction of this valve is best illustrated inFigure 12.

clamped a thin diaphragm: III. ,Withintheupper end of the body;I,I5,"is disposed\a corrugated metal bellows H8, which held in place hy a clamping ring H9. Extendingwithintheybellows IIO is a valve, stem I20, ,the,upper endof which abuts against the upperend of the bellows H8, andthe lower end of which passes through a guide I2 I which is integral withthe upper part of the body II5. Thelower endofthe stem I20 I I seats ina recess I 22 'formedlin the top,of a valve I23 The lower partof the bQ y or casing ;II5 is provided witha fluid outlet I24 disposed below b Arrangedin the controlsystemfw hich @w i llbe understood to be of theqfluid operated type, there -'I"he valve consists of a holllow'two-part body, lli iand a cover 'IIS, between which there is,

duplicated for each va lve l a in the two valve chambers 46. I

as best seen in Figure 1, which enclbsesthe pinion uncovering or opening all of. thefportsilland aifording a normal setting of theval-ve to give the lowest transmission ratio; Obviously, byiorcing fluid into the piston chamberfmfi behiridlthe piston I 09,the piston will be movedagainstthe the part I2I and above'the'valve I23. The valve I23 coacts with a seat I25 of the insert type. and the seat I25 has a calibrated orifice I25 therethrough, the size of which is determined .by the characteristics'to be desired in the conr trol system;= Formed in the bottom part of the casing H5 is a passage I21, communicating with the oriflce I25, andextending to the outside of the casing 'II5 toperr'nit theentrance of the fluid in the control system under certain conditions of operation of the pilot valve. The cover II5 onthe upper end of the casing H5 is preferably provided with a vent I28. An air intake passage I29 is provided in the upper end of the pilot valve casing II5-to admit air or permit the reduction of air pressure in the chamber I30 in which the bellows IIB-is positioned below the diaphragm II I, this admission of air into the chamber or-reduction of air pressure within the chamber I30 serving to-control theopening and closing, respectively, of the valve I23resp'ecting itsseatl25.

v r Snifting-valve Also forming a part of the automatic control system, I provide another valve SV, which I have termed a snifting valve, and which is best illustrated in Figurell. This valve regulates the action' of the pilot valve previously described It consists'of a bodyor casing I3I having two chambers, I32 and I33,,in its lower and upper ends respectively. The bottom of the lower chamber receives a plug I34 having an orifice I355. The plug I34 constitutes a seat for a valve I36. I31 designates a connection for a. line forming a part of the automatic control system, which line is adapted to communicate with the interior of the valve chamber I32.

The upper chamber I33 is closed by a threaded sleeve I38 which encloses a helical spring I39.

Extendingfupwardly from the valve I36 through the body I3I is a valve stem I40, the upper end of the stem being received in a suitable recess or guide I formed in the upper closedend of the sleeve I39. The lower end of the spring I39 seats in a cup-shaped member I42, which in turn rests on a shoulder I43 formedon the valve stem I40. Pressur'e'on the valve I36 may be regulated by screwing the sleeve I38 inwardly or outwardly of the chamber I33.

control system assembly and" general operation Automatic changed as desiredto afford automatic control of I the transmission ratio where the prime mover is of a diiferent'type. The principles involved will be readily understood from the following de-- 'scription.

E generally designates a prime mover of the internal combustion enginetype, which is adapted to be connected with the input shaft 3 of the transmission. The system represented in Figure 10 has been designedprimarily to suit the characteristics of a gasoline engine where a wide range of torque and speed is required at both the inafter become more apparent.

input and output ends of the transmission. Such conditions are met in automotive work. It has been found from past experience that the power developed by a gasoline engine at a given speed is approximately proportional to the absolute pressure in the intake manifold, or expressed in a different way, the power is inversely proportional to the vacuum in the manifold. The intake manifold of the engine E has been designated I50, and from this manifold there extends a conduit 'I5I which is connected to the pilot valve PV in'communication with the passage I29 in' the latter, this conduit I5I forming one of the of the pilot valve PV is connected by a conduit I53 to the intake passages 3| and 82 of the small gear pump A, and also, by means of a. conduit I54 to the intake passages 9| and 92 of the small gear pump B. The passage I 21 of the pilot valve PV is connected to the discharge port 83 of the gear pump A, by means of a'conduit I55, and also to the discharge port 93 of 'the gear pump B, through means of the conduit I55. Discharge port 84 of gear pump A is connected through a conduit I5] to the passage IOI leading into the piston chamber I00'behind the piston I03 which controls the by-pass valve 95. A relief valve R1 is interposed in a line I59 extending between the lines I54 and I5'I. Interconnecting the lines I54 and I55 is a line I59, and line I55 is also connected with the port. I0] which leads into the piston chamber I09 of the cylinder I05, in which the rack actuating piston I09 is slidably mounted. The discharge port 94 of the gear pump B is connected by means of a line I00 to the coupling having the passage 99 therein leading into the piston chamber I00 ahead of the piston I03 and near the end of the chamber. Brand R3 are additional relief valves which are interconnected in the control system, as particularly shown in Fig-. ure 10. These relief valves may be termed bleeders, and are simply calibrated orifices, which may or may not be provided with means to regulate the flow of the control fluid through the areinterposedoin the line I55 at opposite sides of the point of connection of line I59 therewith, and serve to prevent fluid from flowing back to the small gear-pumps A and-B when either of these pumps isslowed down or stopped. F is a by-pass' valve which is interposed between the lines I54 and'l59 in the relationship to the other parts of the control system, as illustrated in Fig.

ure 10. This by-pass valve F can be utilized to establish a condition known as free wheeling,

whichis to say that the output shaft 4 of the transmission is permitted to attain a relatively higherv speed than the input shaft, as will here- Also this valve F establishes a neutral condition of the transmission when the valve is open, so that no power will be transmitted, as is desired when initially i i i I starting the prime mover E or when other con ditions so require. I Having described the general features of the control system and of theautomatic type of a transmission with which the control system is associated, the operation, which, is iully auto-.

matic, will now be described. Assumingthat the 16 I I e continue to be recirculated through thetransmisengine E is running idle atavery low speed, the I small gear pump A will not sion in a manner previously described herein. This circulation of the working fluid in the transmission is caused by the difierential motion between the planetary gears 8 and the central gear I of themain pump unit I, which produces a pumping action. The working. fluid is drawn from the chamber 28 and the motorend of the transmission through the annularj passage 21 into the inner casing 6 of the pump unit, half of the fluid going directly to the near ends of the 1 planetary gears 8, and the other halfoi the fluid being directed through the passages 6' in the pump casing 0 to the far end of the planetary gears. After passing through the gears the "working fluid is discharged through the ports 20 in the central gear 1 into the tube I8 which directs it to the motor unit 2, where it passes through annular passage to the valve cylinders or chambers 46 and 51. The'by-pass ports 96 being open, the'working fluid escapesthere- I through into passages 64 and 64' in the motor casing and returns to the chamber 20, fromw'hich the working fluid may againbe withdrawn'by the pump mum to be recirculated,

At the same time that the wrking iluid is being circulated inthe thansmissiomas just described, the small gear pump A is delivering fluid to the piston chambers I00 and I06, but as the pump is running at low speed, the quantity of fluid pumped is small and escapes readily through the pilot valve PV and relief valve R1 without building up enough pressure to move the pistons I03 and I09 against the pressure of the springs I04 and II, respectively, associated with said v pistons.

Now if the speed of the engine E is raised to a point beyond the idle condition of the transmission which'has just been described, that is, to a point beyond the starting speed of the transmission, the small gear pump A will then deliver more fluidto the piston chamber I 00 than the, relief valve R1 can discharge without building up enoughpressurein back of the piston I 03 to overcome the pressure of the spring I04. Consequently, the piston 103' will be movedfto the" right, as viewed in'FiguresIO and 13, causing by-pass valve to close the byI-pass port 96.

The working fluidin the transmissionmust now flnd an outlet through the motor unit of the transmission, and it therefore passes to the'valve chambers and thence through ports 41 to the motor gears 29, 30, 30, forcing these motor gears to rotate and deliver power to theoutput shaft 4. At the same time, the central gear Tot the pump unit I, which isrigidly fastened tci- 'the central gear 29 of the motor unit 2, starts to rogear 29, and this rotation of the gear I reduces the relative motion of the plane-. tary gears 8, and reduces the quantity of working completely close alLot' the ports 41,- in which I justdescribed would not is to say the transmission would assumeits. low-s a relatively high rate of ample, when the throttle ofthe engine chamber I30 or the pilotvalve,

system to escape through passage IILI of which the transmission H 7 been broughtto a stop. Let it be assumed that -I fluid flowing through the pump unit Iuntil it just meets the requirements of the it output end oithe transmission. t I I 1 I If the-engine speed is now further increased to the po'int at whichthesystem has beenyde- I signedto change the transmission ratio, the fluid which continues to escape through the orifice I26 and passage I21 of I the pilot valve PV willbuild up a pressure at a predetermined engine speed which is sufficiently great to overcome the pressure of the spring, lIlassociated with the piston I09, and thereby cause thevalve 49 in each of the valve chambers ,46 to rotateto a position C108!- ing certain of the ports 41. :I A stable condition Q the fluidpressure is quickly reached and the adjustment of the valveslhas'justdescribed, is

maintained, with a consequent increase in the transmission ratio, until a further change inthe engine speed is made. Further increases in engine speed produce still higher pressures in the piston chamber I 06, withtcorresponding move ments of the connected parts and corresponding increases in transmission ratio, until acondition is establishedtwherein the rotary valvesI lfl case, the input shaft 3, pump gears 1, I, 0, motor gear 29 and output shaft i, all rotate together asa unit. During these various changes mJIthe transmission ratiopthe by-pass passage 06 in the motor'unit 2 is maintained closed by the by-pass valve, 95 under theinfluence oi'the fluid pressure created behind piston IN by the smallg'car pumpA I I t I lt I If the engine speed be now decreased, the regulating parts will go through the reverseibf the as operationsjust described,-until the rotary va lves are fully opened, which is the condition establishing the lowest transmissionratio. If the engine speedlis dropped stillfurther to anidling" speed, the. pressure behlndvpiston lu will be rev- ,duced to a point where it is-overcome' bythe spring I04,--and the by-pass port 96 will be i openednallowing theworkingj fluid to' by-pass around themotor unit of" the transmission and circulate through the tra'nsmission without transmitting powerjfrom the input side of the transmission to theoutputside. 1 l I So much of the control system operation es be entirely satisfactory for automotive work by reason of the fact that it frequently happens in -traflic that it is neces-' sary for theIvehicleto move at arelatively low rateof speed,1and to attain this, the transmission would have to moveinto "low gear, which est ratio condition, with the engine running at speed, which, offcourse, would be uneconomical erator. 'It is to obviate thisconditionjthat the pilot valve PV and snifter valve SV have been incorporated in the control system. For, ex-

, E w open, there willbe little vacuum mime upper I and the valve in willrise freely from its seatand allowthe control fluid in the lines 01' this part0! the control Under this condition, the speed otfthe engine aloneflw ill control the transmissionflratlo of the, transmission.. ,such a conditionwould arise in climbing aj-hill or. in accelerating aiter the vehicle, forms a part, has

Then

the vehicle has, reached the top of a hill.

one of two things may happen, Theoperator 75 and annoyingtothe ops I may keep the engine throttle open so as to at- 1 system.

tain a higher speed, and in this case, the engine speed will continue to control the transmission ratio, and will lock the transmission in high", that is, the maximum transmission ratio condition, when the speed of the engine becomes high eno=.z ..1 to cause operation of the valves 49 of the motor unit of the transmission, closing all of the ports 47, as hereinbefore described. On the other hand, the operator may feel that the speed is high enough and may partially close the throttle to maintain a slightly lower' speed.

Then, the increased vacuum caused by the partial closing of the engine throttle, pulls down on the diaphragm I ll of the pilot valve PV, and

causes the valve I23 to close, or at least partially close, so that the pressure of the control fluid must be increased in order to escape from the pilot valve. This additional control fluid pressure will. operate upon pistons I09, causing the rotary valves 49, which are actuated by these pistons, to assume positions suiting the operating conditions of the engine.

In traffic, with a closed throttle, the -vacuum in the pilot valve PV will hold the valve I23 on its seat at practically any speed 01' the engine, so

that the vehicle would continue to move at a slow pace with the transmission in its highest ratio condition. A sudden opening of the engine throttle, for quick acceleration, would immediately relieve the vacuum in the pilot valve PV,

and the excess pressure in the piston chambers I06 would be'relieved and the rotary valves 49 would. automatically assume their positions affording a low transmission ratio to suit the engine. speed. A closure ofthe engine throttle would again send the transmission into its high .valve PV, and may be adjusted to the personal equation of the operator, or to meetthe 'particu lar conditions of use of thetransmissi'on, such as, for example, the topographical or trafiic conditions'in the case of automotive applications. This snifting valve serves. to bleed air into the line I52 between the engine manifold -I50--and the-pilot valve 'PV, and thereby adjust the vacuum acting upon the diaphragm III.' The air enters through the orifice I35'in the plug I34 at the bottom of the body I3I of. the shifting valve, and passes by the valve I36 to the port I31 and thence into the suction line I5I. By screwing the sleeve I38 of thesnifting valve inwardly or outwardly respecting the body or casing I3I, the pressure exerted by the spring I39 upon the valve I38 can be regulated,thereby regulating the degree of opening of the valve I36, and the vacuum required to causet'hisvalve to open or be held open.

As previously. mentioned, provision is made for causing the transmission to assume a condition permitting free whe'eling.;,Thisis accomplished by opening the byepass valve F in. the control Opening this valve relieves all pressure behind piston I03, and the spring I04, associated with this piston, will immediately move the piston I03 and the main by-pass valve 95 of the motor unit of the transmission to a position opening the by-pass port 96. The valve F may be left open, or it may be closed after the engine has reached an idling speed. The main by-pass 15 valve 95 will not close the Icy-pass port 99 if the valve F is closed while the engine is running at idling speed, but as soon as the engine is speeded up again, the by-pass port 96 will be closed by the piston 95. i

Let it be assumed that the vehicle is moving at high speed with the transmission control system conditioned for free wheeling, and the operator desires to couplethe transmission to the engine so as to attain the normal driving relation. In such a case, as soon as the engine speed re ones a predetermined speed at which the valve 95 normally closes, the main by-pass valve 95 will close the bypass port 96, in which case, the gears of the main pump unit of the transmission will be locked rigidly together. With the engine running at low speed and the vehicle at high speed, such a condition mightprove disas- I trous since it would impose extreme strains upon theparts of thetransmission. To obviate this condition, the small gear pump B has been provided. This pump is connected to the piston open position by virtue of the pressure produced by the small gear pump B upon the control fluid acting upon the piston I03. In other words, the -main by-pass valve 95 cannot close until the small gear pump A develops a greater pressure which is adequate to overcome the back pressure of the small gear pump B acting upon the piston I03. small gear pump A attains a speed at least as high as the speed of the small gear pump B, and

, therefore, the engine and load will be synchronized before the coupling through the transmission takes place.

The other side of the smallgear pump Bis also used to establish a tree wheeling condition under certain circumstances. For example, with the engine dead, the rotary valves 49 would assume open positions establishing the lowest transmission ratio regardless of the vehicle speed. In such a case, the. motor unit 2 of the transmission would act asa pump, and the fluid would berapidly circulated through the various passages of the transmission. This might heat the fluid and produce a considerable internal resistance, so to avoid this, a line from the small gear pump B is connected with the piston chambers I06, and the fluid pressure built up by the small gear pump B causes the pistons I09 to asduty work, however, some modifications may be necessary or desirable in order to increase the capacity of the pump and motor units i and 2 in taking care of the higher powers, and at the same time, to maintain the compactness of construction and keep the weight down to practical limits. Instead of having the planetary gears 8 disposed exteriorly of the central gear I of the pump unit I, the main gear 'I might be made larger and provided with teeth on its interior surface so that the planetary gears might be disposed within the main gear, thereby giving to the pump a much greater capacity than it has in the form illustrated. A similar change might be made in the arrangement of the gears of the motor unit 2. I

This balance is not attained until the gears of the gear pumpunit I.

used herein, means the motion of the working fluid produced by the relative motion or the While the specific details have been herein shown and described, the invention is not con- 1. In ,a hydraulic power transmission mecha nism, a stationary housing, a hydraulic. gearpump of constant volumetric capacity and. a hydraulic gear motor of variable capacity mounted in opposite ends of said housing, and the former comprising a central gear and a planetary,

gear, and the latter comprising a central gear and an auxiliary gear having a fixed axis, a

casing rotatably mounted in the pump end of the housing, said casing rotatably supporting the planetary gear of the pump and having passages therein fordirecting a hydraulic medium from a source within the housing to, the pump gears,

a driving member to rotate said pump casing,

a driven member connected tofthe central gear of the motor, and means for conducting the'hydraulic medium from the pump to the motor gears whereby to transmit motion from the "driving member to the driven member.

2. Apparatus as defined in claim 1, wherein the central gear of the pump isof hollow COIlStI'llO-r tion and is provided with ports through which o the hydraulicmedium pumped. by the pump is; "directed into the space within the gear, and; the central gear is also providedwith a tubular; ex-

tension leading to and directly connected with the central gear of the motor and serves to con duct the hydraulic medium from the pump to the motor.

3. Apparatus as defined in claim 1, whereinthe central gear of the motor is axially open for. re-

ceiving and conducting thehydraulic medium therethrough, and said housing having passages in the motor end thereof for directingthe hydraulic medium from within the central gear of the motor into motor operating relation respect ing the central and auxiliary gears of the motor.

4. Apparatus as defined in claim 1, wherein the hydraulic medium conducting means includes a rotary valve mounted in the housing at the motor end and adapted to progressively coact with a plurality of ports communicating with the motor gears whereby to vary the capacity of the motor responsive to rotative adjustment of. the valve and consequently vary the transmission ratio.

5. Apparatus as defined in claim 1, wherein the hydraulic medium conducting means includes a valve chamber interposed between the pump and the motor, the housing at the motor end having a plurality of ports leading from the ,valve chamber to the motor gears, and the ports being axially spaced relatively to thegears, and a valve rotatably mounted in said valve chamber, said valve comprising a partly cylindrical body having ,one edge inclined relatively to the axis thereof and adapted to progressively coact with th e spaced ports aforesaid whereby .to vary the capacity of the motor responsive to rotative ad-1.

justment of the valve and consequently vary the transmission ratio.

6. Apparatus as claimed in claim 1; in com? bination with adjustable by-pass. valve means interposed in the hydraulic medium conducting means and positioned within the housing at the diumaround the motor through the hydraulic a 9 motor end and exteriorlyof the motor whereby to direct the hydraulic, medium to its source without acting uponthe motor when the by-passvalve means'isin one positionof adjustment. I M

7. Apparatus as claimed in claim l fwherein the hydraulicmedium conducting means includes, a valve chamber interposed, between the pump and the motor, the housing at the motonend having a passage leading from the valve chamber to the source of hydraulic'medium, andfby pass valve means disposed in said valve nem ber and selectively operable, to by-pass the hy'-,{ draulic medium rromtn pump to its source without acting upon the motor. fj .8. Apparatus as claimed inflclaim 1, wherein; the housing at the motor, end is provided with, a plurality of valve chambers arranged concentri cally about the axis of the central gear of the motor, and is also provided with a plurality of 20 spaced ports leading, from one of said chambers to the motor gears,'valve meanspmounted: m me last mentioned chamber adapted to progressively. coact with the ports aforesaid whereby to vary,

the capacity of the motor. and consequently the transmission ratio, and by-pass valve means mounted in another of the valve chambers'and, selectively operable to by-pass the hydraulic me- Q medium conducting means.

9.In a hydraulic power transmission mech nism, a hydraulic medium circulation system, a, hydraulic gear pump of constant volumetricca pacity and a hydraulic gear motor of variable capacity disposed in said system, a driving member operatively connected withsaid pump, ,al driven member operatively connected to said motor so as to be actuated by theIatterresp nsive to circulation'of the hydraulic mediumin the system under the influence of the pump, and, pressure responsive means" operable independently of the pressure of the hydraulic medium in the pump and motor circulation system for varying the capacity of the motor andjconsequently the transmission ratio, said pressure responsive means including means automatically operable in accordance with the load on the driven member.

10. Ina hydraulic power transmission memenism, a hydraulic medium circulation system, a hydraulic gear pump of constant volumetric capacity and a hydraulic gear motor ofvariable capacity disposed in said system, a driving member operatively connected with said pump, a driven member operatively connected to saidmotor so as to be actuated by the latter responsive to circulation of the hydraulic medium in the system under the influence of the pump, and pressure responsive means forvarying the capacity of the motor and consequently the transmission ratio, said pressure responsive means including adjustable valve means disposed in the circulation system intermediate the pump and the motor, an auxiliary pump disposed in the circulation system and operable at a speedwhich isproportional to the speed of the drivingmember, and

pressure changes produced in the systemby said auxiliary pump for' adjusting'the valve means aforesaid.

11. Apparatus as claimed in claim 10 wherein the auxiliary pump is operatively connected with the driving member so as to be driven thereby.

12. Apparatus as, claimedinplaimlO, in combination with pressure means perable by, the j auxiliary pump for by-passing the hydraulic me- "75 fat means automatically operable responsive to the o responsive means interposed in the hydraulic me dium circulation'system for normally by-passing the hydraulic medium around the motor without acting upon the same, an auxiliary pump operatively connected with the driving member for actuating the hydraulic medium by-passing means to its non-by-passing condition, and means interposed between the auxiliary pump and the hydraulic medium by-passing means for render ing said auxiliary pump ineffective on the bypassing means whereby to establish a free wheeling condition between the driving member and driven member.

14. Apparatus as claimed in claim 13, in combination with a second auxiliary pump operatively connected with the driven member and operable upon the hydraulic medium by-passing means to normally maintain the said by-passing means in by-passing condition'when the transmission is conditioned for free wheeling until the driven memberis synchronized with the driving member.

15. In a hydraulicipower transmission mechanism, a hydraulic medium circulation system, a hydraulic gear pump of constant volumetric capacity and a hydraulic gear motor of variable capacitydisposed'in said system, a driving member operatively connected with said pump, a driven member operatively connected to said motor so as to be. actuated by the latter responsive to circulation of the hydraulic medium in thesystem under the influence oi'the pump,

pressure responsive means for varying the capacity of the motor and consequently the transmission ratio, an auxiliary pump disposed in the hydraulic medium circulation system and connected to the driving member so as to be driven by the latter and acting upon the pressure responsive means whereby to vary the capacity of the motor responsive to the speed of the driving member,and adjustable valve means interposed betweenthe auxiliary pump and the pressure responsive means for regulating the pressure produced by the auxiliary pump upon the pressure responsive means.

16. Apparatus as claimed in claim 15, in combination with an internal combustion engine having an intake manifold, and wherein the valve means is pressure responsive and the adjustment thereof is adapted to be effected in response to the pressure in the intake manifold of the internal combustion engine.

17. The combination with an internal combustion engine. having an intake manifold, of a transmission comprising a driving member adapted to be connected with the engine, a hydraulic pump unit operatively connected to the driving member, a hydraulic motor unit operatively connected to the pump unit, a driven member operatively connected to the motor unit, a source of hydraulic medium communicating with the pump unit, means for conducting the hydraulic medium to the motor unit, and means automatically operable by the pressure in the intake manifold aforesaid and speed of the engine for regulating the flow of hydraulic medium from the pump unit to the'motor unit, and con-- sequently regulating the transmission ratio.

18. In a transmission 'of the class described, a

driving member, a hydraulic pump unit comprising a central gear and a planetary gear meshing therewith, a source of hydraulic medium supply communicating with the pump unit, means for imparting planetary motion to the planetary gear of the pump unit responsive to rotation of the driving member whereby to create a flow of the hydraulic medium, a. hydraulic motor unit comprising a main gear and a second gear meshing with said main gear and having a fixed axis, said main gear of the motor unit being positively connected to thecentral gear 01 the pump unit, means for conducting the hydraulic medium from the pump unit to the motor unit and from the motor unit back to the source of supply, whereby to impart motion to the gears of the motor unit responsive to the flow of hydraulic medium from the pump unit to the motor unit, and a driven member positively connected to'the main gear of the motor unit.

19. In a transmission of the class described, a driving member, a hydraulic pump unit comprising a central gear and a planetary gear meshing therewith, a source of hydraulic medium supply communicating with the pump unit, means for imparting planetary motion to the planetary gear of the pump unit responsive to rotation of the driving member whereby to create a flow of the hydraulic medium, a hydraulic motor unit comprising a main gear and a second gear meshsaid main gear of the motor unit being positively connected to the central gear of the pump unit, means for conducting the hydraulic medium from the pump unit to the motor unit and mm the motor unit back to the source of supply, whereby to impart motion to the gears of the motor unit responsive to the flow of hydraulic medium from the pump unit to the motor unit, a driven member positively connected to the main gear of the motor unit, and means for regulating the flow of hydraulic medium to the motor unit, whereby to regulate the flow of the hydraulic medium in the pump unit and consequently the transmission ratio.

'20. In a transmission of the class described, a driving member, a hydraulic pump unit comprising a central gear anda planetary gear meshing therewith, a source of hydraulic medium supply communicating with the pump unit, means for imparting planetary motion to the planetary gear of the pump unit responsive to rotation of the driving member whereby to create a flow of the hydraulic medium, a hydraulic motor unit comprising a main gear and a second gear meshing with said main gear and having a fixed axis, said main gear of the motor unit being positively connected to the central gear of the pump unit, means for conducting the hydraulic medium from the pump unit to the motor unit and from the motor unit back to the source of supply, whereby to impart motion to the gears of the motor unit responsive to the flow ofhydraulic medium from the pump unit to the motor unit, a driven member positively connected to the main gear of the motor unit, and means for regulating the flow of hydraulic medium to the motor unit, whereby to regulate the flow of the hydrauhe medium in the'pump unit and consequently 1 enco es 21. In a transmission of the class described, a

driving member, a hydraulic pump unit comprising a central gear and a planetary gear meshing therewith, a source of hydraulic medium supply communicating with the pump unit, means for imparting planetary motion to the planetary gear of the pump unit responsive to rotation of the driving member whereby to create a flow of the hydraulic medium, ahydraulic motor unit comprising a main gear and a second gear meshing with said main gear and having a fixed axis, said main gear of the motor unit being positively connected to the central gear of the pump unit, means for conducting the hydraulic medium from the pump unit to the motor unit and from the motor unit back to the source of supply. whereby to impart motion to the gears of the motor unit responsive to the flow of hydraulic medium from the pump unit to the motor unit,

.a driven" member positively connected to the main gear of the motor unit, and means for regu-- lating the flow of hydraulic medium to themotor unit, whereby, to regulate the flow oi. the hydraulic mediumin the pump unit and consequently the transmission ratio, said last named means including valve means automatically operable responsive to'the variations in the speed of and power developed by the driving member.

22. A hydraulic variable speed power transmission, comprising a driving member and a driven member, a working fluid interposed therebetween and having such relation thereto that the power of the driving member may be transmitted to the driven member, and means for establishing a free wheeling" relation between the driving and driven members, andmeans operable by the working fluid for maintaining such relation until the speed of the driven memberapproximately equals the speed of the driving member.

mvm n. Momma. 

